Hello I found solution for slow booting for this boards: Select OS Selection to Intel Linux in Bios - only problem is that at most bioses this option is hidden (Default is Windows ). I found that after reading: https://www.cnx-software.com/2017/10/26/mele-pcg35-apo-apollo-lake-mini-pc-review-part-3-ubuntu-17-10/ (this board is j3455 based)   To change that I've used tools from https://winraid.level1techs.com/t/tool-guide-ami-setup-ifr-extractor-amisetupwriter/32801